(1) Field of the Invention
The present invention relates to an improvement in a melting and holding furnace for processing aluminum and other metals.
(2) Description of the Prior Art
A known melting and holding furnace will be described with reference to FIGS. 5 and 6 of the accompanying drawings. In the melting and holding furnace A', a raw material of aluminum is fed from a material preheating tower 20' to a melting chamber 21' continuous with the tower for heating and melting the material. Molten aluminum is then transferred to a holding chamber 8' communicating with the melting chamber 21', where the molten aluminum is heated by a sustaining burner 9' to be maintained at a selected temperature. The molten aluminum is removed little by little, for casting, from a well 5' communicating with the holding chamber 8'.
With such a known melting and holding furnace A' used for melting aluminum, the well 5' cannot be integrated with, the melting and holding furnace A' since the material preheating tower 20' and melting chamber 21' are provided separately. There is thus the disadvantage of a large overall configuration requiring a large installation space.
The melting chamber 21' includes a melting burner 4' which is a gas burner directed horizontally for producing, in elongated forms and with a weak jetting force, red reducing flames having a large infrared content. This prior construction has a disadvantage (1) of low operating efficiency. The material fed is little oxidized because of the reducing flames, but the flames sweep and melt only the faces of the material opposed to the flame jets, with its rear faces of the material being out of reach of the flames. This leaves a large unmolten amount of material at the side remote from the flames. The operator must open a door 22' to the material preheating tower 20' to shove the unmolten material down into the melting chamber 21'. There is also a disadvantage (2) of low thermal efficiency. Because the melting burner 4' has a weak flame jetting force and because the melting burner 4' is directed horizontally, hot air flows contacting the material to be preheated produce little turbulence in the melting chamber 21' and just ascend, gently without effectively preheating the material. Further, there is a disadvantage (3) of poor operating efficiency in that the weak flame jetting force results in a slow melting speed, and the long time taken for melting the material in turn results in low thermal efficiency.
The components of the known furnace are labeled with the same numbers as are used for corresponding components of the furnace of the present invention, with primes affixed thereto for distinction.